Add the hostApp to the state GET v3 result

[thgreasi]

Depends-on: #1502
Depends-on: https://github.com/balena-io/balena-api/pull/4825
Change-type: minor
See: https://balena.fibery.io/Work/Task/Add-hostOS-to-target-state-endpoint-1615

[Page-]

Can this be merged with getUserAppState?

[thgreasi]

I tried to do so, but felt it was a bit too aggressive. We could combine all 3 getSystemAppState, getUserAppState & getAppState to something like:

const getAppState = (
	device: AnyObject,
	targetReleaseField:
		| 'should_be_running__release'
		| 'should_be_managed_by__release'
		| 'should_be_operated_by__release',
	config: Dictionary<string>,
	defaultLabels?: Dictionary<string>,
): StateV3[string]['apps'] | null => {
	let application: AnyObject;
	let release: AnyObject | undefined;
	if (targetReleaseField === 'should_be_running__release') {
		application = device.belongs_to__application[0];
		release = getReleaseForDevice(device);
	} else {
		release = device[targetReleaseField][0];
		if (!release) {
			return null;
		}
		application = release.belongs_to__application[0];
	}

	return {
		[application.uuid]: {
			id: application.id,
			name: application.app_name,
			is_host: application.is_host,
			class: application.is_of__class,
			...(release != null && {
				releases: buildAppFromRelease(
					device,
					application,
					release,
					config,
					defaultLabels,
				),
			}),
		},
	};
};

What do you think?